Good day. I've been operating my Central boiler for 10 years with no problem. The boiler is about 75 feet from my house and heats a concrete floor. This summer I am building a barn which I also intend to heat via pex in a concrete floor. My problem is how to get cold water to the barn to mix with the hot water from the boiler. My well is about 250 feet from the barn and getting cold water from the house to the barn would require drilling into my concrete floor filled with pex or the concrete foundation - both options aren't ideal. An engineer friend suggested taking the cold return from the house and instead of returning the cold water to the boiler, run it in the ground without insulation (to cool it down) and use it as my cold water supply for the barn. The end result would be two supply lines coming off the boiler (one to house, one to barn) and only one return line coming from the barn. My concern is that connecting the two systems sounds like a problem waiting to happen. Any suggestions would be welcome.
Need cold water to mix for new building
- Thread starter Barry Schoharie
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iit is illegal to mix boiler water with potable water for any purpose. That is why back flow preventer's
are installed on boiler feed water lines.
OK why are you doing this???? if you expect to use it for
wash water at a sink your asking for trouble.
You would be miles ahead of things if you simply had a small electric water heater for
hand washing using a large tank of water feeding the water heater and a small self
priming centrifugal pump with a bladder tank for storage for the supply of potable cold water.
If not you need to make things clearer.
are installed on boiler feed water lines.
OK why are you doing this???? if you expect to use it for
wash water at a sink your asking for trouble.
You would be miles ahead of things if you simply had a small electric water heater for
hand washing using a large tank of water feeding the water heater and a small self
priming centrifugal pump with a bladder tank for storage for the supply of potable cold water.
If not you need to make things clearer.
maple1
Minister of Fire
My problem is how to get cold water to the barn to mix with the hot water from the boiler.
Uh yeah - why do you want to do this?
An engineer friend suggested taking the cold return from the house and instead of returning the cold water to the boiler, run it in the ground without insulation (to cool it down) and use it as my cold water supply for the barn.
Sounds like that would drain your boiler.
Something must be getting lost in the translation here...
[You should be able to drill a hole through a foundation with the proper drill. Or come up the outside of a wall just a bit then through the wall and enclose & insulate/heat tape the short section of outside pipe.]
Uh yeah - why do you want to do this?
An engineer friend suggested taking the cold return from the house and instead of returning the cold water to the boiler, run it in the ground without insulation (to cool it down) and use it as my cold water supply for the barn.
Sounds like that would drain your boiler.
Something must be getting lost in the translation here...
[You should be able to drill a hole through a foundation with the proper drill. Or come up the outside of a wall just a bit then through the wall and enclose & insulate/heat tape the short section of outside pipe.]
I apologize for not being clear. I need to mix in cold water because the boiler water temp is 175-185 and water flowing through a concrete floor can only be between 110 and 130 degrees - its not for potable water. So, I'm looking for a way to cool down the water so its safe to flow through the floor.
The only safe way to do this is to bury a loop of pipe in the ground as you have no way to install tempering valve.
Rather than doing this with in floor heating it would be so much simpler to use a long low radiator or two to do the job and make the plumbing
dumb and simple AND save money.
no need to make a mountain out of a mole hill as you have a forest eater for heat.
Rather than doing this with in floor heating it would be so much simpler to use a long low radiator or two to do the job and make the plumbing
dumb and simple AND save money.
no need to make a mountain out of a mole hill as you have a forest eater for heat.
maple1
Minister of Fire
Can't you just use a mixing valve as would normally be done? That mixes some of the return water after it circulates through the floor, with the incoming hot water - with the rest of the return water going back to the boiler? Supply & return pipes would go in the same trench - so if you're running a hot supply pipe from boiler to barn, the return pipe would follow the same path.
Still seems like I'm missing something.
Also, the idea of running a pipe through the ground to scrub some heat off it so it can serve as cold mixer doesn't sound good - you'd just be wasting heat to the ground. You would also want to keep your boiler return temps (temp of cool water entering the boiler) above 140 to help avoid excessive creosote condensation - which would likely require a near-boiler mixing loop also (referered to as return temp protection).
maple1
Minister of Fire
Not sure how the well you mentioned in the first post fits into the picture then.
Although the system is not pressurized it is still closed in the sense that it has a limited water capacity. You just can't keep adding water. Install a mixing valve that will inject return water back to the supply to maintain the desired temperature. The valve has three ports. One from the boiler, one from the return and one to the supply to the emitters.
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Barry, I agree your issue is solved with a traditional mixing valve, which is exactly what is on my system and I have no external water supply at all. Hot boiler water, as hot as 190F+, goes to the mixing valve which I have set at 100F. The mixing valve mixes the hot boiler supply water with the in-floor pex return water to provide the 100F hot water supply to the in-floor pex. The excess hot water from the boiler then is returned to the boiler. In my case, all this happens via a 1000 gallon storage tank. Simple, inexpensive, no moving parts other than the circulator to move water through the floor.
I have the floor controller set to maintain the floor temp at a constant 61F which keeps the shop at a very comfortable working temperature.
I have the floor controller set to maintain the floor temp at a constant 61F which keeps the shop at a very comfortable working temperature.
Leon makes a good point. Your CB will have constant 175-180 degree water. That's different than a gasser/storage setup than many on here use. Why not just have hot water baseboard for only a few hundred bucks vs. a few thousand on in floor pex? I run a household dehumidifier in summer months and it's like the place has AC.
Thank you jebatty, Fred61 and maple1 - you're right - I thought that the return water would still be too hot for the mixing valve but I see in the Central Boiler schematics that it is a recommended set up.
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